The term "connection oriented lines" indicates, as the people skilled in the art know, lines intended to convey signals pertaining to a specific application. The term "application" is used to indicate an apparatus, a service, a network. For additional clarification on AAL1 services, reference can be made to the standardization documents ITU-T I.362, I.363.
The present invention has been developed with particular attention to its possible use to interface an ATM network operating at 34 Mbit/s both with conventional telecommunications networks (terrestrial or via satellite), and with terminals offering broad band services (multimedia services).
Typical examples of the related connection lines are those based on the G.703 interface at 2 Mbit/s and on the RS449 interface with bit rate N.multidot.64 kbit/s.
As is well known, ATM transport techniques have the purpose of enhancing the efficiency of telecommunications networks in terms of flexibility, reconfiguration capability and transport capacity, according to criteria providing for the organization of the flows transported into so-called cells. Such cells are routed within the ATM network according to dynamic schemes able to attain an optimal adaptation of the network exploitation to the transport requirements.
In order to transport on an ATM network data flows conveyed over connection lines of the type mentioned previously, until now it has been suggested to create within the ATM network a durable connection (albeit constituted according to the typical operating modes of the ATM network) between the two nodes involved in the transport. This connection is maintained, with its pre-established, fixed band, throughout the time interval during which the information flow is transported. This also occurs when the band actually needed for transport is reduced, at least temporarily. In practice, a connection destined to transit over the network is always allocated 34 Mbit/s even when the transport requirements of the connection are in fact lower.
Taking into account that the essential advantage of an ATM network is indeed allowing the simultaneous, multi-point transport of multiple information flows with a continuous adaptation to the actual transmission needs, it is evident that the operating modes described above are scarcely efficient in respect of network utilization and, as a consequence, for the user himself, who has to take on the costs of the connection regardless of its actual full exploitation.